1. Field of the Invention
The invention relates to a surgical gripping instrument to be introduced into body cavities.
2. Background Art
Surgical gripping instruments are well known in the art. An exemplary structure is one including a manual operating device associated with a transmission cable having a cable sheathing and a cable core. Gripping elements are coupled to the end of the cable core on the patient's side. The gripping elements have connection parts controlled by the end of the cable sheathing on the patient's side which is movable relative to the cable core or by an end sleeve connected with the operating end of the cable sheathing. The end of the cable sheathing is connected with a finger hold of the manual operating device and the cable core connected with a thumb hold of the manual operating device. The thumb and finger holds are movable relative to each other to effect relative motion of the cable sheathing and cable core.
Such a surgical gripping instrument is used especially for the purposes of bronchoscopy, bulboscopy, coloscopy, duodenoscopy, endoscopy and gastroscopy.
In a surgical gripping instrument of the type described, a thumb hold is connected with the end of the cable sheathing on the operating side and an index finger-middle finger hold is connected with the end of the cable core on the operating side. If the handling physician or the surgical nurse bring the index finger-middle finger hold closer to the thumb hold, the core is retracted relative to the cable sheathing on the patient's side and the connection parts of the gripping elements move into the cable sheathing or the end sleeve with the consequence that the gripping elements are closed in a tong-like manner. Tissue specimens can be gripped and taken.
The following disadvantages have been recognized in the surgical gripping instruments art. When the index finger-middle finger hold is pulled back in the direction of the thumb hold, the thumb hold remains essentially stationary based on the normal coordination of fingers on the human hand whereas the index finger-middle finger hold is moved from its original position and towards the thumb. This means that as the index finger-middle finger hold approaches the thumb hold that the gripper, which is connected with the index finger-middle finger hold by way of the cable core, moves also in the direction of the thumb hold and away from the tissue specimen to be gripped.
However, it is frequently extremely difficult to adjust the gripping elements inside the body relative to the tissue specimen to be taken. Further, the region about the tissue specimen must be illuminated by way of light sources running parallel to the cable to observe the adjustment. Therefore it is undesirable if during the closing of the grippers this adjustment is lost again by a retracting motion of the gripping elements.
It is an objective of the invention to develop a surgical gripping instrument of the type mentioned above in such a way that, during the operation of the manual operating device by means of thumb and fingers in a manner corresponding to the natural motion of the human hand, the gripping elements do not change their position relative to the tissue spot to be gripped. In other words the closing motion of the gripping elements does not change the adjustment of the gripping elements relative to the tissue.
The solution according to the present invention is to firmly connect the thumb hold of the manual operating device with the end of the cable core on the operating side. The index finger-middle finger hold of the manual operating device is connected with the end of the cable sheathing on the operating side and is connected with the thumb hold through a direction reversing gear in such a way that, when the index finger-middle finger hold approaches the thumb hold, the cable sheathing moves in the direction of the gripping elements.
Furthermore, the invention affords a simple, low cost construction for the direction reversing gear which efficiently utilizes space. To meet this additional demand which is subordinate to the aforementioned problem, the direction reversing gear includes a pinion which is placed on a shaft connecting the thumb hold with the end of the cable core on the operating side. The index finger-middle finger hold is movable along this shaft. On the index finger-middle finger hold there is fastened a first rack element which meshes with the pinion. Extending lengthwise of the shaft is a second rack element which also meshes the pinion at a position diametrically opposite the first rack element. The second rack element is connected with a mounting for the end of the cable sheathing on the operating side.
An especially simple and space-saving construction results if the pinion is placed inside a recess in the shaft. The index finger-middle finger hold encloses the shaft which is movable within a shaft passage channel. Within the index finger-middle finger hold is a holding chamber for the rack element which is firmly fixed relative to the index finger-middle finger hold and is situated adjacent the shaft passage channel. Also adjacent the shaft passage channel within the index finger-middle finger hold is a guide channel for the second rack element which is movable relative to the index finger-middle finger hold.
In a well-known manner the thumb hold can be made as a ring which can be slid on the thumb up to the root of the thumb. The index finger-middle finger hold can be made as a spool-shaped roller body. The design of the thumb hold and the finger hold is conventional. Because the design of the holds is well known and the relative motion of the holds relative to each other in operation the same as conventional gripping instruments, a readapting of a person familiar with an old construction to a new manner of operation, is not necessary. Rather, the manner of operation remains entirely unchanged. However, the disadvantage of the previous construction is eliminated which was the fact that the gripping elements retracted from the tissue spot to be gripped. The device as defined in the invention can be used, for instance, in connection with grippers where the connection parts are made in one piece with the gripping elements and the gripping elements carry out a tong-like closing motion when the end of the cable sheathing or the end sleeve approach the connection parts.